Electric rotary furnace



NOV. 1947- F. E. HATCH 71 ELECTRIC ROTARY FURNACE Filed Feb. 5, 1945 5 Sheets-Sheet l EWW W Nov. 4, 1947. HATCH 2,430,171

ELECTRI C ROTARY FURNACE Filed Feb. 5, 1945 5 Sheets-Sheet 2 [Hz 5271b? Femvc/s E /7 rcH Nov. 4, 1947. F. E. HATCH 2,430,171

ELECTRIC ROTARY FURNACE Filed Feb. 5, 1945 3 Sheets-Sheet s Fig.4?

Patented Nov. 4, 1947 2,430,171 ELECTRIC ao'raar FURNACE Francis E. Hatch, Little Rock, Ark, assiznor of one-half to Frances V. Hatch and one-half to Tempest B. Jones Application February 5, 1945, Serial No. 576,310

Claims.

This invention relates to an electrically heated rotary furnace.

The present invention more particularly relates to an improved construction of the type of rotary electric furnace disclosed in my prior Patents Nos. 640,283, issued January 2, 1900, 741,333, issued October 13, 1903, 946,727, issued January 18, 1910, and 1,665,546, issued April 10, 1928. The present invention incorporates all of the objects and advantages of the rotary electric furnace illustrated in, these prior patents and, in addition, embodies certain new advantages effected by the improvements incorporated therein.

In accordance with the principles of my present invention, I provide a rotary electric furnace in which, as in the above mentioned prior patents, the electrical heating units are embedded in the refractory lining of the rotatable shell, but in which the means for cooling the shell, preheating the air or other gas, and utilizing said pre-heated air or other gas in the treatment of the material to be processed in the furnace are more effectively incorporated into the furnace construction and more efficiently controlled than in my prior forms of apparatus. In my present construction, such means comprise one or more blowers mounted on and carried by the rotatable shell of the furnace for rotation therewith, a plurality of pipes extending along the inside surface of the shell and embedded within the refractory lining thereof, with the discharge ends of said pipes opening adjacent the feed end of the furnace in the direction of feed of the material into the furnace, and one or more manifolds in flow communication from the blower, or blowers, to said pipes. By virtue of my improved construction, air or other gas may be introduced into the furnace in the direction of flow of the material being processed to effect either oxidation or reduction of such material, as circumstances may require.

Additionally, my present invention includes thermometric control means for controlling the amount of air or other gas introduced into the furnace by means of said blower, or blowers, in accordance with the temperature, obtaining within the furnace at some particular point, or points, as for instance at the discharge end thereof, whereby the flow of air or other gas may be regulated to maintain the optimum temperature conditions for the carrying out of the particular process intended.

My present rotary furnace construction also embodies new and improved features with respect to the feeding and discharge ends of the furnace. Both the feeding and discharge ends are entirely sealed except for the mechanism required for feeding in the material to be processed and that required for the removal and recovery, if desired, of the gaseous and solid products of the process carried out in the furnace. At the discharge end of the furnace, there is provided a casing having a portion that surrounds and seals the discharge end of the furnace, and said casing is provided with a flue for the removal of the gaseous products of the reaction and with a conveyor for the removal and discharge of the solid or semi-solid products of the reaction that takes place within the furnace. There is, thus, provided a construction that makes possible the complete, or substantially complete, recovery of both the gaseous and solid products of the process carried out in the furnace.

My present construction of rotary electric furnace furthermore makes possible a closer regulation of the conditions within the furnace, such as the oxidizing or reducing conditions obtaining in the furnace, temperature conditions and times of contact between the material being processed and the gases utilized in processing such material.

It is therefore an important object of this invention to provide a rotary electric furnace of improved construction for realizing the advantages above set forth.

It is a further important object of this invention to provide in a rotary electric furnace more efllcient means for controlling the volume and temperature of air or other gas introduced into the reaction zone of the furnace, wherein such means include one or more blowers mounted on the rotatable shell of the furnace for rotation therewith and connected to one or more manifolds for supplying the air or other gas to a plurality of pipes extending lengthwise of the shell and adjacent to the inner surface thereof, whereby such air or other gas may be pre-heated to the desired temperature before being discharged into the reaction zone of the furnace, the discharge ends of said pipes being so arranged with respect to the feed of materials into the furnace as to flow in the direction of such feed and become intimately mixed with said materials.

Other and further important objects of this invention will be apparent from the disclosures in the specification and drawings.

On the drawings: Figure l is a broken, longitudinal sectional view of a rotary electric furnace embodying the prin- 619165 of. my invention, with parts in elevation.

the accompanying Figure 2 is an end elevatonal view taken substantially along the line II-II of Figure 1, with parts in section.

Figure 3 is a sectional view taken substantially along the line III-III of Figure 1.

Figure 4 is a sectional view taken substantially along the line IV-IV of Figure 1.

Figure 5 is a sectional view taken substantially along the line V-V of Figure l.

The reference numeral l (Fig. 1) indicates generally the body portion proper of a rotary electric furnace embodying the principles of my invention. Said body portion comprises an outer cylindrical shell I l which may be of any suitable metal, lined with fire brick, or other refractory material, indicated generally by the reference numeral 12. The shell H is provided at its feeding end with a head l3 secured to the flange end of said shell by means of bolts l4. Said bolts l4 also serve to attach to said head l3, as by means of brackets l5, a collecting ring l6 formed of copper or other good electrical conducting material. At the discharge end of .said shell N there is a somewhat similar arrangement, comprising a head I! secured to the flanged end of said shell by means of bolts l8, brackets I9 also secured to said head IT by means of said bolts i8, and a second collecting ring 20 carried by said brackets l9. Insulating bushings 2| and 22 serve to insulate said brackets l and i9, from the heads I3 and I1 and the bolts l4 and I8, so that said collecting rings [6 and 20 are completely insulated from the body of the furnace. The purpose of the collecting rings l5 and 2% will be explained hereinafter.

The body portion ID of the furnace carries a pair of annular tracks 23 and 24 near the feed end and toward the discharge end, respectively, of the shell H. Said tracks 23 and 24 rest upon and bear against small rollers 25 and 26, respectively, which are supported from cross beams 21 and 28. The cross beams in turn are supported by longitudinally extending I-beams 29 and 30 (Figs. 1 and 2). In order to compensate for a thrust should the furnace body portion I0 be positioned at an angle inclined to the horizontal, there are also provided a pair of thrust rollers 3| and 32 supported from said cross beam 21 and 28 and adapted to bear against opposite vertical faces of the annular track 24.

The driving mechanism for the furnace comprises a large annular gear 33 suitably secured to the shell I and adapted to mesh with a driving gear 34. The stub shafts of the driving gear 34 are encased in dustproof bearings 35 mounted upon a support 36, and said gear 34 is driven by a motor 3?.

The refractory lining l2 includes an outer layer |2a and an inner layer 12b, both of which layers are made up of individual bricks suitably held in place and united together. The individual bricks 38 and the outer layer |2a are notched at their outer mating faces to provide continuous grooves 39 (Figs. 1, 3 and 4) that extend longitudinally of the shell I I and along the inner surface thereof for substantially the full length of said shell. Adjacent the feeding end head l3, both the outer and inner linings |2a and I2b are cut away as at 40 to provide radially extending grooves that join the longitudinally extending grooves 39. A pipe 4| is positioned in each of the longitudinally extending grooves 39, Each pipe 4| has a radially extending extension 42 that passes out through one of the radially extending grooves 40. The extremity of each of the radial extensions 42 of the pipes 4| is offset to provide a discharge opening, as indicated at 43.

Said offset ends of the pipe extensions 42 are circumferentially spaced about a tubular member 44 which serves for the introduction into the furnace of the material to be treated. Said tubular member 44 extends through an opening in the head [3 provided for the purpose and is sealed therein by means of a stufllng box 45. A worm conveyor is operatively positioned within said tubular member 44 for advancing material introduced into said tubular member through a hopper 41. The drive means for the conveyor 45 comprises. a motor 48 having a sprocket 49 that is connected through a drive chain 50 with a sprocket 5| secured on the extended end 52 of said screw conveyor 46. A standard 53 serves to support both the motor 48 and the extended end 52 of said conveyor 45.

At the discharge end of the furnace, the head I 1 is provided with a cylindrical extension 54 (Fig. 1) having an inside diameter the same as that of the inside diameter of the inner lining III). A casing, indicated generally by the reference numeral '55, serves to receive said extension 54 and is sealed thereto by means of a stufllng box 56. A flue 51 leads of! from the top of the casing 55 for the removal of any gaseous products of the process carried out within the furnace. At the lower portion of the casing 55, there is positioned a screw conveyor "which extends out through a cylindrical extension 59 of said casing, Material removed from the bottom of the casing 55 is discharged through a discharge opening 50. A motor 5| drives the screw conveyor 58 through a chain 82 trained around a sprocket 63 on the motor drive shaft and asprocket 64 on the extended end 65 of said screw conveyor. The motor and screw conveyor are supported by vertical supporting members 66.

A pair of blowers 61 and 81a (Figs. 3, 4 and 5) are mounted upon opposite sides of the shell [I near the discharge end thereof. Said blowers 61 and 61a discharge into a pair of manifolds 68 and 68a that extend about the periphery of the shell H to substantially enclose the same. Said manifolds 58 and 68a are tapered in the direction of flow of the gas discharge from said blowers to provide cross-sectional areas of progressively decreasing size.

As is best shown in Figure 1, the manifolds 58 and 68a enclose the open groove ends 38 so as to be in communication with the ends of each of the pipes 4|, the shell H being apertured, as at 65 to -provide entrance into each of said end groove portions 39. Accordingly, air or other gas taken through the openings 10 and 70a into said blowers 61 and 61a is caused to flow through the respective manifolds 58 and 68a, into the pipes 4| and to be discharged through the open ends 43 of said pipes in the direction of travel of the material fed into the furnace through the tubular member 44.

The means for heating the furnace comprise a plurality of electric resistance elements 1| (Figs. 3 and 4) which extend the full length of the furnace and which are embedded inthe refractory bricks of the layer i2b. As best shown in Figure 2, the ends of said electrical resistance elements H at the feeding end of the furnace are connected by means of wires 12 to the collecting ring l6. At the discharge end of the furnace, the corresponding ends of the electrical resistance elements H are similarly connected to the collecting ring 20. Since the connections at both ends are identical,

only those at the front end, as illustrated in Figure 2, will be described.

A bus bar 13 is mounted adjacent to the collecting ring l6, but in spaced and conforming relationship thereto. Said bus bar 13 carries a plurality of copper gauze brushes I4, which are pivotally supported from said bus bar upon copper rods 15. Individual springs I6 secured at one end to a copper rod 11 extending from the bus bar 13, bear at their free ends against said brushes 14 to urge the same into good electrical contact with the collecting ring 15. A cable 18 connects the bus bars 13 at the respective ends of the furnace to a suitable source of electrical current such as a shunt wound direct current generator 96 (Fig. 2). A thermometric control 91 responsive to a thermocouple -88 in the lower part of the discharge end casing 55 (Fig. 1) is connected to the shunt winding of the generator. Electrical current is furnished to each of the motors 80 and 80a (Fig. 4) for the blowers 61 and 61a by wires 8! and Ma connected to collecting rings 82, of which there would be three for a three-phase circuit such as illustrated. A separate brush 83 is provided for each of the collecting rings 82, and the brushes are mounted, as previously described, upon a bus bar 84, with individual springs 85 urging said'bus bars into contact with the respective collecting rings. A cable 86 connects the bus bar 84 with a suitable source of current for driving the motors 80 and 80a.

Th function of the blowers 61 and 61a is to furnish pre-heated air, or other gas, for the reaction that is to be carried out within the furnace. In passing through the longitudinally extending pipes ll the gas serves to cool the shell ll, while at the same time being pre-heated by the heat that is transferred from the electrical resistance elements H through the lining layers l2 and Ho. This pro-heated gas is then discharged from the open ends 43 into the interior of the furnace in the direction of flow of the material being treated.

In order to control the amount of gas delivered by the blowers 61 and 67a in accordance with the requirements, as determined by the temperature of the gases at some particular point, or points, I provide a thermometric control mechanism, indicated at 81 (Fig. 4) which is responsive to such temperature, for instance that at the position indicated by the thermocouple 95 (Fig. 1). In this way the amount of air can be controlled by the thermometric control mechanism 81 in conjunction with the control of the heating elements H by the control mechanism 91 to give the desired temperature conditions within the furnace, Thus, by a joint control of the operation of the blowers 61 and 61a and of the electrical energy fed into the electrical resistance wires 1 l, a very close control indeed of the operating conditions of the furnace can be maintained.

As a further means for keeping the shell ll of the furnace relatively cool, I may provide an overhead sprinkler system comprising an elongated pipe 90 running the full length of the shell I l and provided with a plurality of spaced apertures through which water or other cooling medium is discharged in the form of sprays ill. The pipe 90 is connected to a source of a cooling medium by means of a supply pipe 92.

The conditions within the furnace may be observed by the operator through a peep-hole 98 in the casing 55 (Fig. 1) so as to keep a close check on its performance.

The uses to which my electric rotary furnace may be put are suggested in part in my prior patents previously identified. In general my furnace may be used in connection with the extraction of gold and silver, in the metallurgical treatment of copper, zinc and other ores; in the recovery of sulfur from ores containing sulfides; in the manufacture of sponge iron; carbon for filters; coal and coke products; for the incineration of garbage; for the burning of limestone to produce calcined lime; and for many other purposes. -The close control of temperature and of oxidizing or reducing conditions within the furnace makes it possible to carry out these and various other processes to produce a uniform product with a high degree of efficiency.

It will, of course, be understood that various details of construction may be varied through a. wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. In a rotary electric furnace including a rotatable shell having a refractory lining and heating elements embedded in said lining adjacent the inside surface thereof, means for cooling said shell and for supplying a preheated gas to the interior of said furnace comprising a gas blower mounted on said shell for rotation therewith, an annular manifold connected to the discharge end of said blower and partially surrounding said shell and a plurality of pipes open at one end to said manifold and extending along said lining adjacent the inside of said shell to discharge preheated gas into the interior of said furnace while at the same time protecting said shell from the heat of said heating elements.

2. In a rotary electric furnace including a rotatable shell having a refractory lining and heating elements embedded in said lining adjacent the insid surface thereof, means for cooling said shell and for supplying a preheated gas to the interior of said furnace comprising a gas blower mounted on said shell for rotation therewith, an annular manifold connected to the discharge end of said blower and partially surrounding said shell, said manifold gradually decreasing in cross-sectional area in the direction of flow of the gas from said blower and a plurality of pipes open at one end to said manifold and extending along said lining adjacent the inside of said shell to discharge preheated gas into the interior of said furnace while at the same time protecting said shell from the heat of said heating elements.

3. In a rotary furnace including a rotatable shell having a feeding end and a discharge end, means for feeding material to be treated through said feeding end and mean for withdrawing gaseous and solid products at said discharge end, means for cooling said shell, preheating a gas and introducing said preheated gas into contact with sa d material to be treated, comprising a plurality of pipes extending substantially the full length of said shell on the inside thereof and having discharge ends surrounding said feeding means for discharging a preheated gas in the direction of feed of said material and a blower for forcing a gas through said pipes.

4. In a rotary furnace including a rotatable shell having a feeding end and a discharge end, means for feeding material to be treated through said feeding end and means for withdrawing gaseous and solid products at said discharge end, means for cooling said shell, preheating a gas to said pipes, and a blower mounted on said shell for rotation therewith and connected to said manifold.

5. In a rotary furnace, a rotatable shell, having a feeding and a discharge end, an apertured plate closing said feed end, a tubular member extending through said apertured plate, a screw conveyer in said tubular member for feeding therethrough material to be treated in said furnace, a casing sealing said discharge end having a flue connected to an upper portion thereof, means in the lower portion of said casing for removing solid treated material therefrom, a plurality of pipes extending the length of said shell on the inside thereof with their discharge ends spaced about said tubular member and opening in the direction of feed of said material and a 8 blower mounted on said shell adjacent the discharge end thereof for rotation therewith and connected to said pipes to force a gas therethrough for cooling said shell and to be preheated prior to discharge through the open discharge ends of said pipes.

FRANCIS E.,HATCH.

REFEBEN' E8 CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 741,333 Hatch Oct. 13, 1903 765,666 Hecking July 26, 1904 1,665,546 Hatch Apr. 10, 1926 1,727,036 Rank Sept. 3, 1927 1,800,247 Buckbee Apr. 10, 1926 1,826,847 Vanderweri Oct. 13, 1931 2,007,676 Fulla July 9, 1935 2,073,994 Queneau Mar. 16, 1937 2,084,713 Thayer June 22, 1937 2,112,492 Hoffman Mar. 29, 1938 2,308,332 Irwin et a1 Jan. 12, 1943 

